Integrated biofilter-immersed membrane system for the treatment of humic waters.

An integrated biofilter-immersed membrane study was conducted to determine the effect of placing a biofilter before or after a membrane for the treatment of a humic type water. The parameters measured included total organic carbon (TOC), organic acids, and specific ultraviolet absorbance (SUVA). The difference in membrane fouling and microbial growth for the two configurations was also examined. Greater TOC and organic acid removal occurred when the biofilter was located ahead of the membrane. The greatest decrease in SUVA values was associated with the membrane. The membrane located after the biofilter fouled at a slower rate than the membrane ahead of the biofilter. Fouling was slower when turbidity was present in the synthetic feedwater. A new method is proposed for determining the operational cleaning frequency of membranes, using an empirical model.